This invention relates generally to a truck/trailer box construction having a sidewall structure that is longitudinally straight and laterally curved, and having a concave inside shape and a convex outside shape. More particularly, it relates to the provision of such a sidewall structure that is formed from spaced apart inner and outer skins and longitudinally spaced apart webs that extend between and interconnect the two skins. It also relates to a method of making the sidewall structure and a truck/trailer box utilizing the sidewall structure.
Known truck/trailer boxes that are longitudinally straight and laterally curved, and which have a concave upper side and a convex lower side, are shown by the following U.S. Pat. No. 1,805,489, granted May 19, 1931, to Arthur G. Kerr and Daniel Merchant; U.S. Pat. No. 3,844,616, granted Oct. 29, 1974, to Douglas B. Acre; U.S. Pat. No. 4,948,155, granted Aug. 14, 1990, to Fred T. Smith and Fred P. Smith; U.S. Pat. No. 5,090,773, granted Feb. 25, 1992, to Bernard Guillsume; and U.S. Pat. No. 5,482,359, granted Jan. 9, 1996, to Albert A. Goodson. These patents should be carefully considered for the purpose of putting the present invention into proper prospective relative to the prior art.
There is a need for a way of constructing the sidewalls of the truck/trailer boxes from materials that are very lightweight but yet are strong and rigid. There is also a need for such a truck/trailer box construction that permits the sidewall to be built in sections that can be welded together while allowing for the use of very thin skins and webs that are themselves too thin to be welded. A principal object of the present invention is to fulfill these needs.
A truck/trailer box construction of the present invention comprises a longitudinally straight sidewall structure having a laterally concave inside shape and a laterally convex outside shape. The sidewall structure comprises spaced apart inner and outer skins and longitudinally spaced apart webs, extending between and interconnecting the two skins. In preferred form, the sidewall structure is formed from a series of panels that are welded together at edges where they meet. Preferably, the upper and lower skins and the webs are constructed from an aluminum alloy material, or the like, and are formed by extrusion.
The method of the present invention is basically characterized by providing a sidewall panel structure that includes an upper skin, a lower skin and a plurality of parallel, longitudinally spaced apart, webs, which extend between and interconnect the skins. This sidewall panel structure is roll formed to give it a longitudinally straight and transversely curved shape. To do this, a plurality of forming rolls are provided in a cluster. Adjacent rolls form nips for receiving the panel structure. The panel structure is fed into the nips, with their webs disposed substantially perpendicular to the axis of the rolls. The sidewall panel structure is fed through the rolls several times in order to bend the wall structure a small amount each run through.
The present invention provides a truck/trailer box construction in which the floor and the sides of the box are created without a seam or a weld joint connecting them together. A plurality of long extrusions are used to create the floor and the sides of the box. The extrusions are welded together at their edges to form a single large panel structure that is then transformed by roll forming into a substantially semi cylindrical shape. The resulting box structure preferably has substantially flat upper side portions that extend the full length of the box above the portion of the panel structure that is roll formed. Herein the structure that is formed by welding a plurality of elongated panels together is referred to as sidewall structure even though it also forms a bottom for the box when it is reconfigured by roll forming.
The present invention also permits the elimination of longitudinal supports or stiffeners for the panels that are normally a part of the prior art boxes, which have rounded bottom. The longitudinal supports and/or stiffeners are not needed because the sidewall structure is stiffened by the skins and the webs that extend between and interconnect the skins. The webs are in effect ribs inside the sidewall structure and they are sufficient to provide the strength and stiffening that the sidewall structure needs.
The present invention includes constructing a truck/trailer box from panels of aluminum extrusions and welding the panels together in a way that minimizes loss of strength caused by heat from the welds. In the panel and joint construction of the invention, a substantial part of the heat dissipates in two webs that meet at the joint and in thickened corner regions formed where the webs meet the skins of the panels. The dissipation of the heat from the weld in these regions minimize heat dissipation in the skins of the panel away from the joints where strength is needed.
Other objects, advantages and features of the invention will become apparent from the description of the best mode that is set forth below, from the drawings, from the claims and from the principals that are embodied in the specific structures that are illustrated and described.